This invention relates to electromagnetic projectile launchers and more particularly to burst firing launchers wherein the total burst firing energy can be stored in an inductive energy storage coil.
Rapid firing electromagnetic projectile launcher systems have been proposed in which kinetic energy is stored by revving up the rotor of a kinetic energy storing generator. A fraction of this stored energy would be delivered for each acceleration of a projectile in such a manner that the firing current remains consistent for each shot, thus resulting in a uniform projectile muzzle velocity. Two types of systems have been deemed feasible, one involved a homopolar-inductor combination and the other a rotating pulse generator.
In the homopolar-inductor system, a homopolar generator charges an inductor to the firing current level, and suitable switching fires a projectile. This type of operation is described in commonly assigned copending application Ser. No. 256,745, filed Apr. 23, 1981, wherein some or all of the inductive storage is provided by bore flux augmenting conductors.
With the rotating pulse generator system, the generator produces distinct voltage pulses. In its simplest version, such a generator is connected to the breech rail terminals and, if the breech electrical loop is shorted by the presence of a projectile package, that projectile will be fired because the voltage pulse in combination with all the circuit and projectile-rail parameters results in the desired and consistent accelerating current variation. Barrel and bore configurations particularly suitable for use with a pulse generator are disclosed in commonly assigned copending application Ser. No. 256,745, filed Apr. 23, 1981. In addition, an or for use in such a system is disclosed in copending commonly assigned application Ser. No. 403,955, filed Aug. 2, 1982, now U.S. Pat. No. 4,836,083.
Both the homopolar-inductor and the pulse generator systems have the desirable feature of being able to store sufficient kinetic energy for many shots in a relatively compact, rotating generator. They both suffer the disadvantage that fully charging the rotating machine with sufficient energy for a maximum length burst may take two or three minutes and thus, for immediate rapid fire capability, the rotating machinery may have to remain revved up for hours, though not necessarily at the full speed and, hence, full kinetic energy level. A further drawback of both systems is that the firing rate will tend to decrease for successive shots, though this can be improved by auxiliary equipment or circuitry. In addition, both systems have high stator reaction torque during inductor discharging or firing. Although this can be alleviated by using two counter-rotating rotors for the kinetic energy storage generator, this in turn increases the generator size, weight and cost and complicates the system for accelerating the rotors. Therefore, it is desirable to design an electromagnetic projectile launching system wherein the energy for launching a succession of projectiles is delivered directly by the inductive energy storage means without necessarily supplying any additional energy to that inductance during the burst sequence. For example, the inductive storage means may, in the conventional manner, be charged to the desired first shot current level by a homopolar or other type of DC pulse generator and that generator may also remain connected to the inductive storage means during the firing sequence. However, the generator does not and normally cannot supply sufficient energy to maintain anywhere near constant current for very rapid successive launchings. Copending commonly assigned application Ser. No. 398,539, filed July 15, 1982 by Hughes et al., discloses a rapid burst firing electromagnetic launcher wherein the inductorbarrel system combination results in a significant increase in average bore flux for each successive shot of a burst, and thereby maintains substantially consistent muzzle velocity for each projectile of the burst, while the available launch current decreases.